This invention relates to a telephone system which includes a main device and a telephone set connected to the main device and which further includes a portable terminal connected to the main device through an IP (Internet Protocol) communication network.
In recent years, a so-called internet cafe is wide spread. The internet cafe is a facility, such as a coffee shop or a hamburger shop, which provides a user with a service of offering access or connection to the Internet via a wireless LAN (Local Area Network).
By the above-mentioned service, data communication over IP makes a good progress. As a natural consequence, it is desired to also enjoy smooth speech communication.